T-Mobile is holding a press conference tomorrow to discuss a new way of doing business, which means getting rid of long-term contracts in favor of unsubsidized model that promises more affordable monthly installments in exchange for paying for the full price of your device upfront. As expected, the company has launched new off-contract plans as part of the “Uncarrier” initiative.

These new tiers start at $50 a month for half a gigabyte data and top out at $120 a month 12.5GB of cellular data. Go past the fold for the full breakdown…

• $50 per month for 500MB • $60 per month for 2.5GB • $70 per month for 500MB with tethering enabled • $70 per month for 4.5GB • $80 per month for 6.5GB • $90 per month for 8.5GB • $100 per month for 10.5GB • $110 per month for 12.5GB

These plans include unlimited voice calling, texting and tethering. And being off-contract means you are free to pick any of these tiers without committing your soul to T-Mobile.

Once you spend your allocated monthly allowance, T-Mobile will throttle data, but won’t slap you with an overage fee. If you want unlimited data, that’ll be a $20 extra.

The new rate plans are admittedly competitive in terms of quotas and asking prices, even more so knowing you are not signing a lengthy contract.

It should be interesting seeing how AT&T, Verizon and Sprint react to this.

Recall, if you will, that AT&T last week also launched a bunch of new shared data tiers that are, however, rather pricey and require a contract, going all the way up to a whopping $500 per month for 50GB of data.